270 ROUND THE YEAR 



papilla also revives whenever a feather is accidentally 

 lost. 



Feathers formed in the egg are usually much 

 smaller and simpler in structure than those which are 

 afterwards developed ; they form a soft, downy 

 covering in many fledglings. 



The colours of feathers are due in part to pigment, 

 but very largely to minute structural peculiarities, 

 such as close-ruled grooves or ridges, which give rise 

 to interference colours, like those of mother-of-pearl 

 or Barton's buttons. That the colours of such 

 iridescent bodies are due to the form of the surface 

 was proved by Brewster, who took casts in black wax, 

 and found that they exhibited the same play of 

 colour. The pigments of feathers are mostly black, 

 brown, red or yellow. Green pigment is extremely 

 uncommon in feathers. The green plumage of a 

 Parrot, if held against the light, or crushed, in some 

 cases if thoroughly wetted with water, turns brown, 

 grey or yellow (Gadow). No blue pigment is known 

 to occur in feathers. White feathers are white because 

 of a multitude of reflecting surfaces, never because of 

 the presence of a white pigment. 1 



THE FALL OF THE LEAF. 



Chill October puts an end to the activity of the 

 leaves of our deciduous trees. They cease to be useful 



1 The article on " Feathers " by Dr. Gadow, in Newton's 

 Dictionary of Birds, and " The Interlocking of the Barbs of 

 Feathers," by W. P. Pycraft (Natural Science, Sept. 1893), may 

 be recommended to those who are able to pursue the subject 

 further. 



